Preparation and investigation of bio-diesel using hydrated ethanol as an alternative fuel: A comparative study

Abstract

Free fatty acid in the available crude jatropha oil was found to be 8.1 percent. Therefore, a two-step trans-esterification process was carried out to prepare bio-diesel using hydrated ethanol as reactant. In the first step, pretreatment was carried out to reduce free fatty acid in crude jatropha oil and in second step, base catalyzed transesterification of pretreated oil was carried out to produce biodiesel. Pretreatment reaction was carried out by using (1.5%, 2%, 2.5% and 3.0% v/v of oil) H2SO4 and (24% and 30% v/v of oil) 150° proof, 160° proof, 170° proof, 180° proof and 190° proof ethanol for 1.5 h reaction time at temperature of 70°C respectively. Oil with minimum free fatty acid content obtained from the first step in case of each hydrated ethanol was selected for the second step and the reaction was carried out using hydrated ethanol of same proof which was used in the first step. In second process, alkali catalyzed transesterification of pretreated oil was carried using (1.5 percent, 2.0 percent, 2.5 percent and 3 percent w/v of oil) KOH and different proportions of hydrated ethanol (30%, 40% and 50% v/v of oil) for reaction time 2 h at 70°C. The maximum recovery (66.5%) was obtained when 40% of ethanol (160° proof) and 2.5% KOH was used for transesterification. Fuel properties such as kinematic viscosity, flash point, cloud point, pour point, density and gross heating value of crude jatropha oil, biodiesel and its blends were measured and then compare with diesel.